The present invention relates to a clamping apparatus of an injection molding machine, and especially to a mold clamping apparatus for building a clamping force in equilibrium.
As shown in FIGS. 1 and 2, a conventional mold clamping apparatus of an injection molding machine is illustrated, which includes a fixed platen A1, a movable platen A2, a rear platen A3, two pairs of parallel tie bar A4 at four corners and an ejector apparatus B. The rear platen A3 and the movable platen A2 are connected by a toggle mechanism A5. By a clamping hydraulic cylinder A6 at the end surface of the rear platen A3 to push a crossed head A7, and then the crossed head A7 to drive the toggle mechanism A5, the actions of opening mold and closing mold are performed. Two guide rods A8 are installed between the rear platen A3, crossed head A7 and the movable platen A2 for guiding the crossed head A7 and supporting the ejector apparatus B. Other than a clamping hydraulic cylinder A6, the end surface of the rear platen A3 is further installed with a set of mold adjusting means including a driven motor A9, a driving gear A10, a gear A11, a female screw gear A11, a female screw supporter A12 and fixed plate A13. By the motor A9 to drive the driving gear A10 for driving the driven gear A11. By the motor A9, the driving gear A10 is driven for further driving the driven gear A11, and then by rotation of the driven gear A11, the female screw gear on the four tie bar A4 are driven so that the rear platen A3 will move with the seat of the movable platen A2. Therefore, the object of mold adjusting is achieved and it can be used by molds with different thickness. The ejector apparatus B includes an ejector plate B1, an ejector hydraulic cylinder B2. By the moving of an ejector piston B4, the ejector rod B3 also move therewith so that the object of separating a product from a mold is attained.
As described above, the conventional mold clamping apparatus of an injection molding machine means uses a hydraulic cylinder means as a power source. Therefore, the hydraulic pump, valves, oil circuits, etc. in the mold clamping apparatus will increment the complexity thereof. The operation of the mold clamping is controlled by hydraulic pressure. Thus, the control is very complex and can not be performed exactly. In order to drive the toggle mechanism means to act, the hydraulic pump must be operated continuously for generating a required hydraulic pressure. Moreover, in order to retain a required pressure, a large energy must be consumed. Besides, conventional mold clamping apparatus of an injection molding machine has a problem of oil pollution which is undesired by peoples.
Accordingly, the primary object of the present invention is to provide a mold clamping apparatus for effectively improving the defects in the conventional injection molding machine, such as large power consuming, difficult in maintenance and positioning for substituting the conventional hydraulic power source. Therefore, the structure can be simplified and positioning precision is incremented so that power is saved and oil pollution is avoided.
Another object of the present invention is to provide the mold clamping apparatus of an injection molding mechanism. Other than improving the aforesaid defects of conventional mold clamping apparatus, since two timing belts are used instead of single belt as in the prior art design. Since two symmetric ball screw with two timing belts are used instead of two belts, the unbalance of tension and the timing difference from the driving of ball screw are avoided. Moreover, since symmetric ball screw are used, the mold clamping forces are built. Therefore, the precision and stability of products are improved.
Accordingly, the present invention provides a mold clamping apparatus for an injection molding machine means mainly includes a servo motor installed at the center of the rear platen and two timing belts to drive two ball screw rear platen so as to push a five point inward bending toggle mechanism to open mold, close mold and clamping mold. Moreover, the servo motor fixed to the lateral side of the movable platen drives the nuts to rotate so as to push the ball screw, ejector rod and ejector plate to move linearly for achieving the object of ejecting. A electromotive motor on the rear platen will drive the mold adjusting means. By the assisting of the servo motor on the rear platen, the function and object of automatic mold adjusting can be achieved rapidly.